Well drilling and precompletion method

ABSTRACT

A method of drilling and precompleting a well through a problem earth formation including the steps of: drilling a first upper portion of the well by conventional techniques using a liquid drilling mud to maintain a pressure on the earth formation being drilled and to circulate the cuttings out of the well bore; setting a string of well casing in the first upper portion of the well bore, removing the drilling mud from the well bore; air drilling a lower portion of the well bore through the problem formation; setting an expendable plug in the well bore at a landing nipple along the lower end portion of the upper string of well casing to pressure isolate the lower air drilled portion of the well bore from the upper conventionally drilled portion of the well bore; bleeding the pressure down in the well bore above the plug; running a string of slotted liner into the well bore on a work string for casing the lower air drilled portion of the well bore, including an expending shoe on the lower end of the string of liner and a liner hanger connected with the upper end of the string of liner; closing the well bore at the well head around the work string to control the well during the liner setting; engaging the expendable plug with the expending shoe to activate the plug to equalize the pressure across the plug and to release and expend the plug downwardly from the landing nipple while coupling the plug with the expending shoe; moving the string of liner with the expending shoe and the hanger downwardly in the well bore until the string of liner is disposed along the lower portion of the well bore and the hanger is aligned with the landing nipple in the upper casing string; and securing the hanger with the landing nipple of the upper casing string to support the string of liner from the landing nipple through the lower air drilled portion of the well bore.

United States Patent McCollum WELL DRILLING AND PRECOMPLETION METHOD [75] Inventor: Robert W. McCollum, Allen, Tex.

[731 Assignee: Otis Engineering Corporation, Dallas, Tex.

[22] Filed: Dec. 18, 1974 [21] Appl. No.: 533,763

[52] US. Cl. 166/315; 175/71 [51] Int. Cl. 13218 23/02; E21B 33/10; E21B 43/00 [58] Field of Search 166/315, 285; 175/69. 71

[56] References Cited UNITED STATES PATENTS 2,164,266 6/1939 Armentrout et al. 166/285 2,173,035 9/1939 Armentrout et a1. 166/315 2,252,973 8/1941 Hall et a]. 111111111 166/315 3,011,549 12/1961 Fredd et al. 166/285 3.531.236 9/1970 Braddick et al. 166/285 3,677,340 7/1972 Blount et al, ,1 166/315 Primary Examiner-Stephen J, Novosad Attorney, Agent, or FirmH1 Mathews Garland [57] ABSTRACT A method of drilling and precompleting a well through a problem earth formation including the steps of: dril ling a first upper portion of the well by conventional techniques using a liquid drilling mud to maintain a pressure on the earth formation being drilled and to circulate the cuttings out of the well bore; setting a string of well casing in the first upper portion of the well bore, removing the drilling mud from the well bore; air drilling a lower portion of the well bore through the problem formation; setting an expendable plug in the well bore at a landing nipple along the lower end portion of the upper string of well casing to pressure isolate the lower air drilled portion of the well bore from the upper conventionally drilled portion of the well bore; bleeding the pressure down in the well bore above the plug; running a string of slotted liner into the well bore on a work string for casing the lower air drilled portion of the well bore, including an expending shoe on the lower end of the string of liner and a liner hanger connected with the upper end of the string of liner; closing the well bore at the well head around the work string to control the well during the liner setting; engaging the expendable plug with the expending shoe to activate the plug to equalize the pressure across the plug and to release and expend the plug downwardly from the landing nipple while coupling the plug with the expending shoe; moving the string of liner with the expending shoe and the hanger downwardly in the well bore until the string of liner is disposed along the lower portion of the well bore and the hanger is aligned with the landing nipple in the upper casing string; and securing the hanger with the landing nipple of the upper casing string to support the string of liner from the landing nipple through the lower air drilled portion of the well bore.

15 Claims, 16 Drawing Figures l l Nov. 25, 1975 US. Patent Nov. 25, 1975 Sheet 1 of5 3,921,719

mdE

mdE

US. Patent Nov. 25, 1975 Sheet 2 of5 3,921,719

US. Patent Nov. 25, 1975 Sheet 3 of5 3,921,719

FIGBB U.S. Patent Nov. 25, 1975 Sheet 4 of5 3,921,719

I 3 m w 5 w FIG. 80

FIG; 8C

U.S. Patent Nov. 25, 1975 Sheet 5 of5 3,921,719

WELL DRILLING AND PRECOMPLETION METHOD This invention relates to methods ofdrilling and precompleting wells and more particularly relates to a method of drilling through a problem formation which reacts adversely to water containing drilling fluids.

In the drilling of wells. particularly oil and gas wells. the normal procedure is to pump a drilling fluid which normally is a mud-like liquid generally containing water into the formation to wash the drilled cuttings up the well bore around the drill bit and drill pipe and to impose a hydrostatic head on the formations being drilled so that any natural formation pressure encountered in drilling into oil and gas bearing formations will be safely contained until the drilling process is completed and the well is properly equipped to control the fluid pressures. Occasionally an earth formation is encountered which presents extremely formidable obstacles to continued normal drilling. One such type formation is the Mesa Verde found in the state of Colorado which is a heaving shale or bentonitic formation including a type of clay which swells when contacted by water. When such a formation is initially drilled into, the drilling will proceed in the normal manner for the first several hours of drilling during which water in the drilling fluid soaks from the bore hole into the formation around the hole. The formation then swells causing the drill bit and pipe to stick if drilling is continued. If the drill bit and pipe are pulled from the bore hole the formation may swell to the extent that the previously drilled hole essentially closes. Oftentimes, in actual practice such formations have been drilled over periods of many months with efforts to complete a well having to be abandoned. In one known instance of such a problem a well was drilled for a period of seven months without success in completing it. It has been found. however, that formations comprising heaving shale may be successfully drilled using a fluid such as air for circulation through the well bore to wash out the cuttings and maintain the desired pressure on the formations being drilled. The air does not cause the heaving shale to swell as does water containing drilling mud. A slotted liner is then set in the lower air drilled portion of the well bore. Since the slotted liner may be quite long. such as several thousand feet. the well must be pressure controlled during the insertion of the liner, otherwise the well will flow at the well head through the liner.

It is a particularly important object of the invention to provide a new and improved method for drilling and precompleting a well bore passing through a problem formation such as a bentonitic formation which is particularly sensitive to water containing drilling fluids.

It is another object of the invention to provide a method of pressure control ofa well while drilling and precompleting the well bore which includes drilling an upper portion of the bore by conventional means. thereafter drilling a lower portion of the bore passing through the problem formation by air drilling. and installing a slotted liner along such lower portion of the well bore.

In accordance with the invention there is provided a method for air drilling and precompleting a well bore through a particularly troublesome formation which is especially adversely affected by normal drilling procedures using water containing drilling liquids. The method of the invention includes: drilling an upper portion of the well bore through normal formations by suit able conventional means and installing well casing in such upper portion including a casing landing nipple along a lower end portion of the casing; circulating the drilling mud out of the well bore to the extent that the well bore is substantially dry; air drilling a lower portion of the well bore which passes through the troublesome formation; installing an expandable plug in the casing landing nipple to pressure isolate the lower air drilled portion of the well bore from the upper portion of the well bore; bleeding off the pressure in the upper portion of the well bore above the plug; inserting a work string supporting string of well tools and equipment comprising an expending shoe supported on the lower end of a string of slotted liner supported from a hanger adapted to engage the casing landing nipple; closing the well bore at the wellhead around the work string to control drilling fluids and formation pressures; lowering the liner and tools downwardly into the well bore whereby the expending shoe engages. couples with. and forces the plug downwardly from the casing landing nipple; and lowering the displaced plug. expending shoe. slotted liner, and liner hanger until the hanger is locked in the casing landing nipple thereby supporting the slotted liner along the lower air drilled portion of the well bore. The well is then completed by conventional means for fluid production.

A more thorough understanding of the details of the method of the invention and the apparatus used in earrying out such method together with the foregoing objects and advantages will be obtained from reading the following detailed description taken in conjunction with the accompanying drawings wherein:

FIG. I is a schematic view in section and elevation showing the first step of drilling a well bore in accordance with the method of the invention comprising conventional drilling of an upper portion of the well bore and setting a casing in such portion;

FIG. 2 is a schematic view similar to FIG. I illustrating the next step of air drilling the lower portion of the well bore through the troublesome formation;

FIG. 3 is a schematic view similar to FIGS. 1 and 2 illustrating the step of pressure isolating the lower air drilled portion of the well bore by installation of a plug in the landing nipple of the casing along the upper portion of the well bore;

FIG. 4 is a schematic view similar to FIGS. 1 3 showing the step of displacing the plug downwardly with the expending shoe supported on the lower end of the slotted liner string suspended from the liner hanger;

FIG. 5 is a schematic view similar to FIGS. I 4 illustrating the well bore as precompleted in accordance with the method of the invention;

FIGS. 6A and 6B taken together constitute a fragmentary view in section and elevation of an expendable plug coupled with a running tool in accordance with a preferred embodiment of the invention;

FIGS. 7A and 7B taken together constitute a fragmentary view in section and elevation of the expendable plug fully set in the casing landing nipple at the lower end of the first string of easing installed in the well bore;

FIGS. 8A, 8B, 8C and 8D taken together constitute a fragmentary broken view in section and elevation showing a running tool. a liner hanger, a slotted well bore liner. a plug expending shoe. and the expendable plug coupled together during the running procedure represented in FIG. 4;

FIG. 9 is a fragmentary view in section and elevation illustrating the locking dogs on the liner hanger expanded into the casing landing nipple preliminary to locking the hanger at the landing nipple and expansion of the hanger seals; and

FIGS. [A and 10B taken together constitute a fragmentary view in section and elevation showing the liner hanger fully locked with the seal expanded in the casing landing nipple and the handling tool removed.

Referring to the drawings a well bore is drilled in accordance with the invention using a combination of conventional mud and air drilling techniques utilizing equipment for lining the well bore which includes a first upper string of well casing 21 including a casing landing nipple 22, an expendable plug 23, a plug running tool 24, FIG. 6A. a liner hanger running tool 25, FIG. 8A. a liner hanger 30, a slotted liner 3!, and a plug expending shoe 32. In accordance with the invention the well bore 20 is drilled by conventional techniques using drilling mud to drill a first upper portion of a well bore 20 after which a suitable string of well casing 21 including a casing landing nipple 22 is installed in the well bore. The well is drilled using drilling mud to a depth of within about 200 feet of the formation which is expected to present a drilling problem. The well is then air drilled through the casing 21 downwardly through the problem formation 23 forming a lower air drilled well bore 20b. The expendable plug 23 is installed in the well bore at the landing nipple 22 to confine the air pressure within the well bore portion 20b below the plug while the well bore is opened above the plug to admit the casing liner 31. The expending shoe 32 is secured on the lower end ofthe liner while the casing hanger 30 is connected with the upper end of the liner. The casing hanger is coupled with the handling tool 25 supported from a work string 29 of tubing or drill pipe for lowering the casing hanger liner and expending shoe downwardly in the well bore. After the casing hanger is lowered into the well, pressure control means such as blowout prcventers, not shown, are closed at the wellhead around the work string to keep the well under control during the lowering of the slotted liner. The plug 23 is engaged by the expending shoe forcing the plug downwardly from the casing nipple while supporting the plug from the shoe. The plug, shoe. liner. and hanger are lowered until the liner is within the lower air drilled well bore portion 20b with the liner being permanently installed supported by the hanger from the casing nipple 22.

Referring to FIGS. 10A and 108, the casing landing nipple 22 is a conventional tubular member having upper internal threads 22a for connection with the easing string 21 and an internal locking recess profile which includes an upper internal annular recess 22b. a middle recess 22c, and a lower recess 22d. At the lower end of the recess 22b the landing nipple is provided with an internal annular stop shoulder 22e for supporting the well tools locked in the nipple against downward movement. The landing nipple permits the releasable locking ofthe plug 23 in the hanger 30 at the lower end ofthe upper string of well casing 2|. The use of the multiple recess profile in the landing nipple permits selectivity in the use of the nipple in the sense that only locking keys which have a compatible boss profile may be landed and locked in the nipple while other locking keys on well tools will pass through the nipple during well operations.

Referring to FIGS. 6A and 6B the expendable plug 23 has an inner mandrel 34 formed by a tubular head member 35 and a main body member 40 telescoped together and secured by a pin 4]. The head 35 has an enlarged upper portion 42 provided with an external annular locking recess 43. The main body member has an upper external annular seal boss 44 which supports a pair of seal rings 45, an external annular release recess 50 below the boss 44, and a pair of lower seal rings 51 supported around the lower end portion of the body. The expendable plug has an outer mandrel 52 which is slidably fitted over the inner mandrel 34. The outer mandrel 52 has a reduced upper end portion 53 providing an upwardly facing external annular stop shoulder 54 for the connection of a running tool 55 which is secured with the outer mandrel by a shear pin 60. As shown in FIG. 6B the outer mandrel 52 has an internal annular seal recess 6!, the upper end of which defines a downwardly facing stop shoulder 62 within the outer mandrel. The recess 6] receives the seal boss 44 and the ring seal 45 for sealing between the inner and outer mandrels at the relative positions of the mandrels shown in FIGS. 6A and 6B. The lower end portion of the outer mandrel 52 has an internal annular recess 63 and an external annular flange 64. The mandrel 52 is provided with circumferentially spaced lateral bores 65 in each of which is positioned a locking ball 70. An annular locking head and key retainer 7] is secured on the upper end portion of the outer mandrel 52. The head 7] is connected by a shear pin 72 with the mandrel 52. The shear pin 72 extends through the head 71 into an external recess 73 formed in the outer surface of the mandrel 52. The head 71 has an internal annular upwardly opening conical recess 74 which holds a plurality of circumferentially positioned slips 75 each having a toothed internal surface for gripping the outer surface of the mandrel 52 to hold the mandrel against downward movement relative to the head 71. A coil spring is disposed in the recess 74 between the upper ends of the slips 75 and a spacer ring 81 which is held against the spring by an internal lock ring 82 secured within the upper end portion of the head H. The head 71 is threaded onto a sleeve 83 which tits in sliding relationship around the outer mandrel 52. The lower end of the sleeve 83 is threaded into a lower key retainer 84. A plurality of locking keys are disposed around the sleeve 83 between the head H and the lower key retainer 84 for releasably supporting the expendable plug at a locking recess such as in the casing landing nipple 22. The keys 85 have upper and lower retainer flanges and 91 which are held by corresponding flanges 92 and 93, respectively, on head 7] and the lower key retainer 84. The keys 85 are biased outwardly by springs 94 fitted within internal recesses of the keys around the sleeve 83. Each of the keys has an external locking boss profile which is compatible with the locking recesses 22c and 22d in the casing landing nipple 22 for locking the expendable plug against upward movement in the casing. The keys 85 have upwardly facing locking shoulders 95 which are engageable with the downwardly facing internal annular locking shoulder 22fin the landing nipple 22. The keys 85 are biased constantly outwardly by the springs 94 and serve to properly locate the expendable plug at a compatible landing nipple recess and hold the plug against movement in the desired direction which in the present instance is against upward movement. It will be recognized that the keys 85 cannot be locked or wedged outwardly and thus are pressed inwardly upon downward movement of the plug in passing or being forced from a locking recess. Sufficient lateral movement is permitted the keys 85 so that the keys will freely slide along the inner wall surfaces of a tubing or casing string and will expand into the desired locking recess.

As seen in FIG. 6B the expendable plug 23 has an external annular seal I00 disposed on the outer mandrel 52 between the key retainer 84 and a ring member I01. The member I01 has an internal locking recess I02 which receives the outer portions ofthe locking ball 70 during the steps in the operation of the plug when the seal 100 is relaxed as shown in FIG. 6B and when the seal is expanded as in FIG. 7B. The ring member I0] is threaded onto the upper end of a bottom nose member I03 which has an upper internal annular recess 104 providing an upwardly facing stop shoulder 105. The lower end portion ofthe outer mandrel 52 extends into the recess 104 with the lower end edge of the mandrel engaging the stop shoulder 105 at the relative position of the plug members shown in FIG. 6B. The nose member 103 has a pressure equalization side port IIO. The member I03 is secured by a shear pin III to the lower end of the inner mandrel 34 ofthe expendable plug. By manipulation of the inner and outer mandrels 34 and 52 of the expendable plug the plug may be set and released during the initial and final phases of the operation of the well apparatus as described in more detail hereinafter. The plug is designed to isolate the lower air drilled portion 20b of the well bore from the upper portion 20a to confine the air drilling fluid pressure within the well bore below the plug prior to running in the slotted liner 3!.

The liner hanger 30 used to support the slotted liner 3] in the well bore from the casing landing nipple 22 is illustrated in detail in FIGS. 8A and 8B which show the hanger as it is run into the well bore and in FIGS. 10A and 10B illustrating the hanger locked in the casing landing nipple 22. Referring to FIGS. 8A and 8B the liner hanger 30 includes a tubular body mandrel 120 formed by an upper mandrel section 12] and a lower mandrel section 122. The upper mandrel section is threaded into a head member 123 which is provided with an inwardly extending handling lug 124. A guide head 125 is threaded on the upper end of the head member I23 provided with an inwardly sloping upper end guide surface 130 to guide a handling tool such as the tool 25 into the upper end of the liner hanger. A ring seal I3] is carried by the head member 123 within an internal annular recess 132 at the lower end of the member to seal between the mandrel section 121 and the head member I23. A seal assembly 133 including upper and lower identical seals I34 separated by a spacer ring I35 is disposed on the mandrel section 12] below the head member 123. An annular slip retainer and seal assembly support member 140 is mounted on the mandrel section I21 below the seal assembly I33. The member I40 has an internal annular recess I4] which includes a conical upper portion I42 which holds a plurality of circumferentially spaced slips 143. The slips I43 are biased upwardly by a spring I44 so that the toothed inner surfaces of the slips engage the outer surface of the mandrel section I21 to resist upward movement of the mandrel which tends to tightly wedge the slip within the conical recess portion 142 between the mandrel section and the member 140. The

member I40 is secured by a pin 145 to a tubular key mandrel which is connected along an upper end portion by a shear pin 151 to the slightly enlarged head portion 122a ofthe mandrel section 122. The key mandrel has a pair of longitudinal windows 152 each of which accommodates a locating and locking key I53 which has an outer profile compatible with the inner profile of the casing landing nipple 22 for locating the liner hanger at and locking the hanger in the landing nipple. Each of the keys I53 has upper and lower retainer flanges I54 and I55 which extend behind lip portions and I61 on the key mandrel I50 projecting into the Windows 152 for retaining the keys with the mandrel and permitting the keys to move radially inwardly and outwardly. Each of the keys is biased radially outwardly by a leaf spring 162 secured at an upper end by a screw 163 within the key. The lower end ofthe key mandrel ISO is supported on a tubular member 164 secured as by welding at 165 to the lower hanger mandrel section I22. Each of the keys has an internal release recess I70 permitting each key to compress inwardly to a release position in the position of the hanger mandrel illustrated in FIG. 8B. The hanger mandrel section 122 is provided with an external annular locking flange I7I secured as by welding at 172 on the mandrel section. When the hanger mandrel is driven downwardly relative to the keys for expanding the seal elements I34 the lower end 122a ofthe head of the lower mandrel section 122 is aligned behind the upper ends of the keys and the key locking flange I7] is aligned behind the lower ends of the keys preventing compression ofthe keys so that the keys will not release from a landing nipple locking recess.

As shown in FIG. 8A the liner hanger 30 is coupled with a handling tool 25 which is a tubular member such as a pipe section having an external J-slot to receive the handling lug I24 of the head member I23 on the liner hanger. The J-slot feature comprises an inverted .lshaped recess which is a standard handling tool feature wherein the vertical portion of the .I-slot opens downwardly to permit entry of the handling lug I24 into the slot and the handling tool is rotated to align the handling lug in the curved closed end portion of the slot so that the liner hanger may hang by means of the lug engaged in the slot from the handling tool. Such .I-slot arrangements are shown in detail in illustrations at page 3951 of the Composite Catalog of Oilfield Equipment and Services. 1974-75 Edition, published by World Oil, Houston, Tex. The lower end of the liner hanger mandrel section 122 is threaded into the upper end portion 3la of the slotted liner 3].

As represented in FIG. 8C the slotted liner 31 is a tubular well casing member which has a plurality of elongated narrow slots 31b distributed circumferentially along the length of the liner to provide lateral support along the well bore wall for the formation while permitting substantial well fluid flow into the well bore from the formation. Thus the liner provides substantial formation wall support along the well bore while permitting ready flow of well fluids into the well bore from the formation.

The lower end of the liner 31 is threaded into the expending shoe 32 which is used to engage, remove, and support the expendable plug 23 when installing the liner in the well bore. The detail features of the expending shoe are shown in FIG. 8C which illustrates the shoe coupled with the inner mandrel of the plug 23 as the plug is released from the casing landing nipple 22 and pushed downwardly in the well bore. The expending shoe includes a tubular housing I80 having an enlarged head end portion I8] threaded on the lower end of the liner. The housing I80 has an internal flange 18I defining a downwardly facing stop shoulder 182 at the upper end of an upper recess 183 which is concentric with a larger lower recess I84 opening through the lower end ofthe housing. The lower end of the housing is threaded into a retainer I85 which has a bore 190 forming a sliding fit with the inner mandrel of the plug 23. A collet I91 is disposed within the bore of the housing I80 for coupling the expending shoe with the plug mandrel. The collet has an annular head portion I92 which fits within the upper bore portion I83 of the housing and has dependent circumferentially spaced collet fingers I93 having locking heads I94 sized to engage the locking recess 43 of the inner mandrel 34 of the expendable plug. The retainer 185 has an enlarged bore portion 190a defining an upwardly facing stop shoulder 19017. When the expending shoe 32 is lifted as seen in FIG. 8C, the collet heads I94 move into the bore portion 190a against the shoulder l90b holding the heads inwardly locked on the upper end of the man' drel 34.

The well tools and equipment illustrated in the drawings are used to carry out an air drilling process and precomplete a well in particularly troublesome areas such as bentonitic formations. In the first step of the process using such tools and equipment the well bore 20 is drilled with conventional techniques such as using liquid drilling mud to form the bore hole portion 200. This portion of the bore hole is drilled to within as close as two hundred feet to what is expected to be the troublesome formation. The location of the troublesome formation 33 as it is designated in the drawings is generally based on past drilling experience in the particular area of the well. After completion of the standard drilling procedures recognized steps are followed to install the tubular well casing 2I which includes substantially at the lower end of the casing the casing landing nipple 22. After completion of drilling with the liquid mud the liquids are removed from the bore hole and the hole is made as dry as possible. Air drilling techniques are then used to advance the hole through the troublesome formation 33 forming the lower portion 20b of the hole. The air drilling techniques include circulating air downwardly through the drill string, outwardly through the drill bit and back up the bore hole through the annulus between the bore hole wall and the drill string. The air is pumped at a sufficient velocity to lift the cuttings to the surface in the usual manner.

At the completion of the air drilling phase forming the bore hole the expendable plug 23 is installed in the landing nipple at the lower end of the casing string 21 to shut in the lower portion of the bore hole which had been air drilled confining air under pressure within such bore hole portion. The expendable plug 23 is connected with the running tool 24 by means of the shear pin 60 as shown in FIG. 6A. The running tool is connected on a handling string 29 used to lower the plug in the well bore. The seal 100 of the plug is relaxed as shown in FIG. 68 with the outer mandrel S2 of the plug being secured by the shear pin 73 to the head member 71 while the inner mandrel 34 of the plug is secured by the shear pin III to the outer mandrel. The plug and handling string are lowered through suitable pressure confining apparatus such as blowout preventcrs, not shown. at the wellhead to confine the air pressure within the well bore while the plug and handling string are being lowered. The plug is lowered through the casr ing landing nipple 22 and then lifted upwardly to latch the keys 85 in the landing nipple recesses. All of the downwardly facing surfaces on the keys 85 taper upwardly and outwardly whereby the keys readily move downwardly as the plug passes through the landing nipple. The only abrupt locking shoulder on the keys is the upwardly facing surface 95. As the plug is lifted upwardly back into the landing nipple the keys expand outwardly into the locking recesses of the nipple with the shoulder 95 on each of the keys engaging the downwardly facing locking shoulder surface 22f of the landing nipple which stops the upward movement of the keys holding the plug at the landing nipple with the keys expanded as shown in FIG. 6A into the locking recesses of the nipplev Upward force is continued on the handling string 29 to expand the seal I00 within the landing nipple and lock the plug at the nipple. The shear pin 72 is weaker than the shear pin 60 so that the pin 72 shears initially releasing the outer mandrel 52 to be pulled upwardly by the handling tool 24 to the position illustrated in FIGS. 7A and 7B. The mandrel 52 is released when the pin 72 breaks so that the mandrel 52 is lifted within the member 71, the sleeve 83 supporting the keys 85, and the seal I00. The member 7I, the sleeve 83, and the keys 85 cannot move upwardly as the keys are locked in the landing nipple. The upward movement of the outer mandrel 52 lifts the locking balls which are confined between the member [M and the inner mandrel since the balls are below the recess 50. The upward force on the balls 70 raises the member 101 against the lower end of the seal 100. The upper end of the seal cannot move upwardly since the keys are holding the member 84 against upward movement so that the seal is expanded radially outwardly as shown in FIG. 7B engaging the inner wall surface along the casing landing nipple recess to seal around the plug mandrel S2 with the landing nipple recess wall. The mandrel 52 is lifted within the slips which are wedged downwardly and inwardly by the spring against the outer wall surface of the mandrel. The slips lock the mandrel against downward movement so that the mandrel is held upwardly to keep the seal I00 in compression expanded outwardly. When the seal I00 is fully expanded the upward force on the handling tool shears the pin 60 releasing the handling tool and string 29 from the plug 23 so that the tool and string are lifted upwardly leaving the plug in the casing landing nipple. FIG. 7A illustrates the lifting of the handling tool from the upper end of the plug mandrel after the pin 60 has sheared. Also in FIG. 7A the upward movement of the mandrel 52 will be evident from the two portions of the shear pin 72, the inner portion being displaced upwardly from the outer portion showing the upward movement of the mandrel. As the outer mandrel 52 is lifted the inner mandrel 34 is raised with the outer mandrel by the pin 111 since there is no force at this time resisting the upward movement of the inner mandrel. Since the outer and inner mandrels go up together they remain in the same longitudinal relationship so that the locking balls 70 remain confined between the mandrels holding the member 101 at an upper end position to retain the seal I00 in the compressed expanded condition of FIG. 7B. The nose 103 is solid below the side portion and since the seals 5I remain engaged with the inner wall of the nose and the seals 45 are in contact with the outer mandrel bore portion 6I the expendable plug 23 fully closes the bore of the casing landing nipple 22 to shut off the lower portion b ofthe well bore retaining such well bore portion under the pressure of the air drilling fluid.

After removal of the handling string 29 and the running tool 24 from the well bore the surface end of the well bore is opened bleeding down the air pressure within the upper portion 20a of the well bore above the plug 23. The upper end of the well bore is opened to permit installation of the liner 3] which can be of very substantial length such as two thousand feet. The expending shoe 32 is secured on the lower end of the bottom section of the liner 3] as illustrated in FIG. 8C. The expending shoe comprises the retainer 185, the housing I80, and the collet I91. The housing 180 is threaded to the lower end portion of the bottom liner section. The liner is then assembled section by section as the liner string is lowered in the well bore until a sufficient length of liner string has been suspended in the well bore at which time the upper end portion of the top liner section is secured by threading onto the lower end portion of the liner hanger mandrel 122 as represented in FIGS. 88 and 8C. The liner hanger is then assembled with the handling tool 25 by insertion of the handling tool into the guide head I25 of the hanger until the J-slot 172 is engaged with the handling lug 124 as seen in FIG. 8A. The expending shoe, the liner. and the liner hanger are thus supported in an assembled relationship from the handling tool 25 as they are lowered on the handling string 29 into the upper portion of the well bore. When the hanger 30 is within the upper casing 21 below the wellhead, not shown, blowout preventers at the wellhead are closed around the handling string so that the well may be pressure controlled after the plug is expended opening well pressure into the upper well bore portion. The liner is then lowered on the work string. When the expending shoe telescopes downwardly over the upper end of the mandrel 34 of the plug 23 the collet 191 of the expending shoe snaps into the locked relationship on the plug mandrel shown in FIG. 8C. The collet 191 is pushed upwardly to the position illustrated at which the collet finger heads 194 are free to expand outwardly to snap over the mandrel head downwardly into the locked relationship illustrated. A downward force applied by the liner string and expending shoe on the inner mandrel 34 shears the pin lll permitting the inner mandrel to be driven downwardly to the lower end position illustrated in FIG. 8D at which the recess 50 of the inner mandrel is aligned with the locking balls 70. The camming force of the member I01 on the locking balls caused by the expanding tendency of the compressed seal I00 forces the balls 70 radially inwardly into the recess 50 so that the member 101 is free to move downwardly on the outer mandrel 52 relaxing the seal 100 so that the seal contracts. As the mandrel 34 is pushed downwardly after the shearing of the pin 111 the seals 45 on the mandrel move downwardly into the larger bore portion 63 of the outer mandrel 52 so that the higher air pressure below the plug 23 is applied through the side port 110 in the nose I03 and upwardly past the seals 45 along the annulus between the inner and outer mandrcls 34 and 52 to equalize the pressure across the plug 23 between the higher pressure lower portion 20b of the well bore and the upper portion 200 of the well bore. The pressure equalization occurs before displacing the plug 23 downwardly from the casing landing nipple. Continued downward force by the liner on the expending shoe after the relaxation of the seal I00 causes the keys to be compressed inwardly as the downwardly sloping faces on the keys engage the downwardly sloping landing nipple recess surfaces. As soon as the keys are compressed inwardly to the position of FIG. 80 the plug 23 is released from the landing nipple and the plug. the liner, and the liner hanger con tinue downward movement as represented schematically in FIG. 4 showing the liner and expendable plug moving into the lower air drilled bore portion 20b. The plug 23 does not drop freely in the well bore but rather is suspended and remains suspended by means of the collet I9I from the lower end of the expending shoe 32.

The displaced plug 23 supported from the suspending shoe 32, the liner 31, and the liner hanger 30 are lowered by means of the handling tool 25 until the keys I53 of the liner hanger reach and expand into the locking recesses of the landing nipple 22 as illustrated in FIG. 9. Since the key bosses are compatible with the two upper landing nipple recesses 22b and 220 the keys readily expand into the recesses when they are aligned with the recesses. The downwardly facing lock shoulder I53a on the keys engages the upwardly facing lock shoulder 22e of the landing nipple so that no further downward movement of the keys can occur. Downward force on the handling tool applied to the upper end of the liner hanger at the handling lug 124 forces the head member 123 downwardly driving the mandrel I20 downwardly while the keys I53 are held against downward movement. The members I50 and I40 together with the expandable seals 134 are held against downward movement by the expanded locked keys. The pin ISI shears releasing the mandrel I20 with the head I23 to move downwardly expanding the seals I34 and driving the mandrel locking flange I71 behind the lower ends of the keys I53 while the head portion I22a of the mandrel section I22 moves behind the upper ends of the keys as shown in FIG. ")8. The spring biased slips 143 engage the outer surface of the mandrel section I21 thereby locking the mandrel at the lower position of FIG. 10B so that the seals 134 are expanded in sealed relationship with the inner wall surface of the landing nipple and the keys I53 are locked outwardly. The liner is thus suspended as schematically shown in FIG. 5 from the liner hanger with the annulus around the upper end of the liner at the hanger being sealed by the expanded seals 134 so that production of well fluids into the casing of the well bore must occur through the slots in the liner 3]. The plug 23 remains suspended from the expending shoe at the lower end of the liner as seen in FIG. 5. The running string is then disengaged from the liner hanger by rotation until the vertical open J-slot portion of the slot 172 is aligned with the handling lug 124 so that the handling tool 25 is lifted freely upwardly from the upper end of the liner hanger 30. The handling tool and string are withdrawn from the well bore which is thereafter fitted out as desired for fluid production from the well.

Thus in accordance with the method of the invention a well bore is drilled by conventional means and processes through earth formations which are compatible with conventional liquid drilling fluids following which a suitable conventional well casing is installed including a casing landing nipple at the lower end of the casing string. The well is thereafter dried out and drilled by air drilling techniques through troublesome formations which are affected by water contained in conventional drilling fluids. Following the air drilling the well is plugged at the casing landing nipple by an expendable plug to confine the air drilling fluid pressure and any formation pressure within the lower air drilled portion of the well bore while the upper portion of the bore is opened to the atmosphere for running in the string of slotted liner. Without keeping the lower portion of the well bore sealed off by the plug. the liner, which may be several thousand feet long. could not be run into a well under pressure. An assembly including the expendable shoe, the required length of slotted well liner or casing, and the liner hanger are assembled and lowered into the well bore. The expendable plug is engaged by the expending shoe. supported in the shoe. and pushed downwardly from the casing landing nipple. The liner supported from the hanger with the expending shoe and displace plug are lowered until the hanger is in locked relationship in the casing landing nipple. The preeompletion of the well is thus finished and the well may be properly fitted for production which may include the lowering of production tubing. valves, and related structure necessary to properly flow and control well fluids coming from the formation upwardly through the well bore.

What is claimed is:

l. A method of drilling and preeompleting a well bore comprising the steps of: drilling a first upper portion of said well bore; drilling a second lower portion of said well bore; pressure isolating said lower portion of said well bore; opening said upper portion of said well bore to the atmosphere; inserting a string of slotted liner in said upper portion of said well bore; closing said upper portion of said well bore above said string of slotted liner; opening said lower portion of said well bore into said upper portion of said well bore to equalize the pressures between said portions of said well bore; and setting said string of slotted liner in said lower portion of said well bore.

2. A method of drilling and preeompleting a well bore in accordance with claim 1 wherein said lower portion of said well bore is air drilled.

3. A method of drilling and preeompleting a well bore in accordance with claim I wherein said lower portion of said well bore is pressure isolated by setting a well plug in said well bore above said lower portion of said well bore. said plug being adapted to hold a pressure in said lower portion of said well bore in excess of the pressure in said upper portion of said well bore.

4. A method of drilling and preeompleting a well bore in accordance with claim 3 including the step of setting casing in said upper portion of said well bore and installing said plug in a lower end portion of said casing.

5. A method of drilling and preeompleting a well bore in accordance with claim 4 including the step of supporting said string of slotted liner from a hanger and engaging said hanger in said lower end portion of said casing.

6. A method of drilling and preeompleting a well bore in accordance with claim 5 including the step of coupling a lower end of said string of well liner with said plug, expending said plug from said lower end por' tion of said casing, and supporting said plug on said lower end portion of said slotted liner as said slotted liner is set in said lower portion of said well bore.

7. A method of drilling and preeompleting a well bore in accordance with claim 6 wherein said upper portion of said well bore is drilled with drilling mud.

8. A method of drilling and preeompleting a well.

bore having a lower portion penetrating a drilling liquid sensitive earth formation comprising the steps of: drilling an upper portion of said well bore; drilling a lower portion of said well bore: sealing off said lower portion of said well bore from said upper portion of said well bore; communicating said lower portion of said well bore with said upper portion of said well bore to equalize the pressures in said upper and lower portions; and setting said well liner in said lower portion of said well bore.

9. A method in accordance with claim 8 wherein said upper portion of said well bore is drilled with drilling liquid and a string of casing is set in said portion.

10. A method in accordance with claim 9 including the steps of opening said well bore at the surface to the atmosphere while inserting said liner into said upper portion of said well bore and closing said well bore at the surface above said liner prior to setting said liner in said lower portion of said well bore.

ll. A method of drilling and preeompleting a well bore having a lower portion penetrating a drilling liquid sensitive earth formation comprising the steps of: drilling an upper portion of said well bore with drilling liquid; setting a string of casing in said upper portion of said well bore. said string of easing having a casing landing nipple along a lower portion thereof; removing the drilling liquid from said well bore; air drilling a lower portion of said well bore; plugging said well bore between said upper and lower portions thereof to retain pressure in said lower portion and keep said well under control; opening said well bore at the surface to the atmosphere to reduce the pressure in said upper portion to atmospheric; running a string of slotted well bore liner into said upper portion of said well bore; closing said well bore at the surface above said string of slotted liner; equalizing the pressure in said well bore between said upper and lower portions thereof; running said string of liner into said lower portion of said well bore; and setting said string of liner in said lower portion of said well bore.

12. A method in accordance with claim 11 wherein said step of closing said well bore between said upper and lower portions comprises installing a removable plug in said well bore adapted to seal against pressure below said plug.

13. A method in accordance with claim 12 including the step of supporting said string of liner from said landing nipple in said casing string along said lower end portion of said string.

14. A method in accordance with claim 13 including the step of coupling the lower end of said liner with said plug and supporting said plug from said liner when said liner is set in said lower portion of said well casing.

15. A method of drilling and preeompleting a well bore having a lower portion passing through a drilling liquid sensitive earth formation comprising the steps of: drilling an upper portion of said well bore with drilling liquid; setting a string of casing in said upper portion of said well bore. said casing having a casing landing nipple along a lower end portion thereof for supporting well tools within said upper portion of said well bore; circulating the drilling liquid out of said well bore to substantially dry said well bore; air drilling a lower portion of said well bore through said drilling liquid sensitive earth formation; running a well plug into said well bore and releasably locking said well plug in said casing landing nipple for closing off said well bore between 13 said upper and lower portions to confine fluid pressures in said well bore below said plug; opening the surface end of said well bore at the upper end of said upper portion to the atmosphere; connecting a string of slotted well bore liner with a work string. said string of well bore liner having an expending shoe secured to the lower end thereof and being coupled with a hanger at the upper end thereof. said hanger being releasably secured with the lower end of said work string; lowering said expending shoe, slotted liner and hanger into said upper portion of said well bore above said plug; pressure sealing said well bore at said surface end thereof at the upper end of said upper portion of said well bore with sealing means adapted to close around said work string and permit said work string to be lowered into said well bore while confining pressure in said well bore 14 at said surface end; lowering said work string engaging said expending shoe with said plug to initially activate said plug to partially open said plug for equalizing the pressures in said upper and lower portions of said well bore; continuing lowering said work string to release said well plug and couple said well plug with said expending shoe for supporting said well plug from said expending shoe; lowering said work string to position said slotted liner along said lower portion of said well bore; engaging said hanger in said upper end of said slotted liner in said casing landing nipple for supporting said slotted liner from said casing landing nipple along said lower portion of said well bore; and disengaging said work string from said hanger and retrieving said work string from said well bore.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent: No. 3921719 Dated November 25 1975 Inventor(s) Robert W. McCollum It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 8, Line 7 after "bore;" insert inserting a well liner in said upper portion of said well bore;

Signed and Sealed this twentieth Day of April1976 [SEAL] I Arrest:

RUTH C. MASON C. MARSHALL DANN AlHSH'Hg ()lficv (nmmissimmr njlurvnts and Trademarks 

1. A METHOD OF DRILLING AND PRECOMPLETING A WELL BORE COMPRISING THE STEPS OF: DRILLING A FIRST UPPER PORTION OF SAID WELL BORE; DRILLING A SECOND LOWER PORTION OF SAID WELL BORE; PRESSURE ISOLATING USED LOWER PORTION OF SAID WELL BORE; OPENING SAID UPPER PORTION OF SAID WELL BORE TO THE ATMOSPHERE; INSERTING A STRING OF SLOTTED LINER IN SAID UPPER PORTION OF SAID WELL BORE; CLOSING SAID UPPER PORTION OF SAID WELL BORE ABOVE SAID STRING OF SLOTTED LINER; OPENING SAID LOWER PORTION OF SAID WELL BORE INTO SAID UPPER PORTION OF SAID WELL BORE TO EQUALIZE THE PRESSURES BETWEEN SAID PORTIONS OF SAID WELL BORE; AND SETTING SAID STRING OF SLOTTED LINER IN SAID LOWER PORTION OF SAID WELL BORE.
 2. A method of drilling and precompleting a well bore in accordance with claim 1 wherein said lower portion of said well bore is air drilled.
 3. A method of drilling and precompleting a well bore in accordance with claim 1 wherein said lower portion of said well bore is pressure isolated by setting a well plug in said well bore above said lower portion of said well bore, said plug being adapted to hold a pressure in said lower portion of said well bore in excess of the pressure in said upper portion of said well bore.
 4. A method of drilling and precompleting a well bore in accordance with claim 3 including the step of setting casing in said upper portion of said well bore and installing said plug in a lower end portion of said casing.
 5. A method of drilling and precompleting a well bore in accordance with claim 4 including the step of supporting said string of slotted liner from a hanger and engaging said hanger in said lower end portion of said casing.
 6. A method of drilling and precompleting a well bore in accordance with claim 5 including the step of coupling a lower end of said string of well liner with said plug, expending said plug from said lower end portion of said casing, and supporting said plug on said lower end portion of said slotted liner as said slotted liner is set in said lower portion of said well bore.
 7. A method of drilling and precompleting a well bore in accordance with claim 6 wherein said upper portion of said well bore is drilled with drilling mud.
 8. A method of drilling and precompleting a well bore having a lower portion penetrating a drilling liquid sensitive earth formation comprising the steps of: drilling an upper portion of said well bore; drilling a lower portion of said well bore; sealing off said lower portion of said well bore from said upper portion of said well bore; communicating said lower portion of said well bore with said upper portion of said well bore to equalize the pressures in said upper and lower portions; and setting said well liner in said lower portion of said well bore.
 9. A method in accordance with claim 8 wherein said upper portion of said well bore is drilled with drilling liquid and a string of casing is set in said portion.
 10. A method in accordance with claim 9 including the steps of opening said well bore at the surface to the atmosphere while inserting said liner into said upper portion of said well bore and closing said well bore at the surface above said liner prior to setting said liner in said lower portion of said well bore.
 11. A method of drilling and precompleting a well bore having a lower portion penetrating a drilling liquid sensitive earth formation comprising the steps of: drilling an upper portion of said well bore with drilling liquid; setting a string of casing in said upper portion of said well bore, said string of casing having a casing landing nipple along a lower portion thereof; removing the drilling liquid from said well bore; air drilling a lower portion of said well bore; plugging said well bore between said upper and lower portions thereof to retain pressure in said lower portion and keep said well under control; opening said well bore at the surface to the atmosphere to reduce the pressure in said upper portion to atmospheric; running a string of slotted well bore liner into said upper portion of said well bore; closing said well bore at the surface above said string of slotted liner; equalizing the pressure in said well bore between said upper and lower portions thereof; running said string oF liner into said lower portion of said well bore; and setting said string of liner in said lower portion of said well bore.
 12. A method in accordance with claim 11 wherein said step of closing said well bore between said upper and lower portions comprises installing a removable plug in said well bore adapted to seal against pressure below said plug.
 13. A method in accordance with claim 12 including the step of supporting said string of liner from said landing nipple in said casing string along said lower end portion of said string.
 14. A method in accordance with claim 13 including the step of coupling the lower end of said liner with said plug and supporting said plug from said liner when said liner is set in said lower portion of said well casing.
 15. A method of drilling and precompleting a well bore having a lower portion passing through a drilling liquid sensitive earth formation comprising the steps of: drilling an upper portion of said well bore with drilling liquid; setting a string of casing in said upper portion of said well bore, said casing having a casing landing nipple along a lower end portion thereof for supporting well tools within said upper portion of said well bore; circulating the drilling liquid out of said well bore to substantially dry said well bore; air drilling a lower portion of said well bore through said drilling liquid sensitive earth formation; running a well plug into said well bore and releasably locking said well plug in said casing landing nipple for closing off said well bore between said upper and lower portions to confine fluid pressures in said well bore below said plug; opening the surface end of said well bore at the upper end of said upper portion to the atmosphere; connecting a string of slotted well bore liner with a work string, said string of well bore liner having an expending shoe secured to the lower end thereof and being coupled with a hanger at the upper end thereof, said hanger being releasably secured with the lower end of said work string; lowering said expending shoe, slotted liner and hanger into said upper portion of said well bore above said plug; pressure sealing said well bore at said surface end thereof at the upper end of said upper portion of said well bore with sealing means adapted to close around said work string and permit said work string to be lowered into said well bore while confining pressure in said well bore at said surface end; lowering said work string engaging said expending shoe with said plug to initially activate said plug to partially open said plug for equalizing the pressures in said upper and lower portions of said well bore; continuing lowering said work string to release said well plug and couple said well plug with said expending shoe for supporting said well plug from said expending shoe; lowering said work string to position said slotted liner along said lower portion of said well bore; engaging said hanger in said upper end of said slotted liner in said casing landing nipple for supporting said slotted liner from said casing landing nipple along said lower portion of said well bore; and disengaging said work string from said hanger and retrieving said work string from said well bore. 